A catalyst composed of a mixture of a metallocene compound and an organic aluminum oxy compound has been widely known as a homogeneous catalyst for polymerizing olefins. There have been made reports on olefin polymerization catalysts composed of various metallocene compounds and linear or cyclic organic aluminum oxy compounds, for example, in Japanese Patent Application Laid-open No. 19309/1983 (European Patent No. 69951), Japanese Patent Application Laid-open No. 35007/1985 (European Patent No. 129368, U.S. Pat. No. 5,324,800), Makromol. Chem., Rapid Commun. 9, 457-461 (1988), etc. However, the biscyclopentadienyl complex base catalysts used in the prior art do not give high molecular weight polyolefins when the polymerization is run at reaction temperatures of 50 to 200.degree. C., which are efficient in industrial processes.
Japanese Patent Application Laid-open No. 2917/1995 reports that high molecular weight polyolefins are obtained by use of an amidinato complex having a trimethylsilyl group on its nitrogen atom, specific examples of which include:
bis(N,N'-bis(trimethylsilyl)benzamidinato)zirconium dichloride, PA1 bis(N,N'-bis(trimethylsilyl)benzamidinato)zirconium ditriflate, PA1 (cyclopentadienyl)(N,N'-bis(trimethylsilyl)benzamidinato)titanium dichloride, PA1 (cyclopentadienyl)(N,N'-bis(trimethylsilyl)benzamidinato)zirconium chloride, and PA1 (pentamethylcyclopentadienyl)(N,N'-bis(trimethylsilyl)benzamidinato)titaniu m dichloride. PA1 L is a group represented by general formula (2) ##STR1## PA1 Cp represents a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group, PA1 m is 1 or 2, PA1 n is 1 when m is 1 or 0 when m is 2, PA1 when m is 1, the L group and the Cp group may be crosslinked to each other, PA1 when m is 2, the L groups may be crosslinked to each other, PA1 X1 and X.sup.2, which may be the same or different, each represent a hydrogen atom, a halogen atom, an organic metalloid group, an alkoxy group, an amino group, a hydrocarbon group, or a hetero atom-containing hydrocarbon group]. PA1 (A) a transition metal compound (A-1) represented by general formula (1) described in 1 above, and PA1 (B) at least one compound selected from the group consisting of an organic aluminum oxy compound (B-1) and a compound (B-2) which reacts with the transition metal compound represented by general formula (1) described above to form an ion pair. PA1 (A-1) a transition metal compound (A-1) represented by general formula (1) described in 1 above, and PA1 (A-2) at least one transition metal compound selected from the group consisting of a transition metal compound (A-2a) represented by general formula (3) ##STR2## PA1 a plurality of (Q.sup.1)s, which may be the same or different, each represent a hydrogen atom, a halogen atom, a C.sub.1-20 hydrocarbon group, an alkoxy group, an aryloxy group, a silyloxy group which may be substituted with 1 to 3 alkyl groups, or a substituted alkyl group containing 1 to 30 carbon atoms of which at least one carbon atom in the skeleton is replaced with an element selected from the group consisting of atoms of Groups 13, 14 and 16 in the periodic table, PA1 Me represents a transition metal selected from the group consisting of atoms of Group 3, 4, 5, and 6 in the periodic table, and PA1 p is 0 or 1], and (A-2b) a transition metal compound represented by general formula (4) ##STR3## PA1 R.sup.22 represents an alkylene group, an alkylidene group, a cycloalkylidene group in which one of ring forming carbons may be replaced by an oxygen atom, a di-substituted germylene or silylene group, disubstituted with an alkyl group or a phenyl group, PA1 Q.sup.2 and Q.sup.3, which may be the same or different, each represent a hydrogen atom, a halogen atom, a C.sub.1-20 hydrocarbon group, an alkoxy group, an aryloxy group, a silyloxy group which may be substituted with 1 to 3 alkyl groups, or a substituted alkyl group containing 1 to 30 carbon atoms of which at least one carbon atom in the skeleton is replaced with an element selected from the group consisting of atoms of Groups 13, 14 and 16 in the periodic table, PA1 Me represents a transition metal selected from the group consisting of atoms of Group 3, 4, 5, and 6], and PA1 (B) at least one compound selected from (B-1) an organic aluminum oxy compound, and (B-2') a compound which reacts with the transition compound represented by general formulae (1), (3), or (4) above to form an ion pair. PA1 L is a group represented by general formula (2) ##STR4## PA1 A and B, which may be the same or different, each represent an atom of Group 15 of the periodic table. More specifically nitrogen, phosphorus, arsenic, antimony, or the like, preferably nitrogen or phosphorus. PA1 D represents an atom of Group 14 of the periodic table, preferably carbon. PA1 A is bonded to M, PA1 B is coordinated to M through a lone electron pair or through a resonance when M, A, D and B are resonant among them. PA1 R.sup.3 represents a hydrogen atom, a halogen atom, an organic metalloid group, an alkoxy group, an amino group, a hydrocarbon group or a hetero atom-containing hydrocarbon group.) PA1 Cp represents a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group. PA1 m is 1 or 2, n is 1 when m is 1 or 0 when m is 2. When m is 1, the L group and the Cp group may be crosslinked to each other, and when m is 2, the L groups may be crosslinked to each other. PA1 X.sup.1 and X.sup.2, which may be the same or different, each represent a hydrogen atom, a halogen atom, an organic metalloid group, an alkoxy group, an amino group, a hydrocarbon group, or a hetero atom-containing hydrocarbon group. PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (Cyclopentadienyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (n-Propylcyclopentadienyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (n-Butylcyclopentadienyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (Indenyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (Trimethylindenyl)(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(fluorophenyl)benzamidinato)zirconium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(trifluoromethylphenyl)benzamidinato) zirconium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(2,6-dimethylphenyl)benzamidinato)zir conium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(naphthyl)benzamidinato)zirconium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(fluoronaphthyl)benzamidinato)zirconi um dichloride, PA1 (Cyclopentadienyl)(N,N'-bis(naphthyl)benzamidinato)zirconium dichloride, PA1 (Cyclopentadienyl)(N,N'-bis(fluoronaphthyl)benzamidinato)zirconium dichloride, PA1 (Cyclopentadienyl)(N,N'-bis(anthracenyl)benzamidinato)zirconium dichloride, PA1 (Pentamethylcyclopentadienyl)(N,N'-bis(anthracenyl)benzamidinato)zirconium dichloride, PA1 Bis(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 Bis(N,N'-bis(naphthyl)benzamidinato)zirconium dichloride, PA1 Bis(N,N'-bis(anthracenyl)benzamidinato)zirconium dichloride, PA1 Bis(N,N'-bis(fluorophenyl)benzamidinato)zirconium dichloride, PA1 Bis(N,N'-bis(methylphenyl)benzamidinato)zirconium dichloride, PA1 Dimethylsilylene(cyclopentadienyl)(N,N'-bis(phenyl)amidinato)zirconium dichloride, PA1 Dimethylsilylene(tetramethylcyclopentadienyl)(N,N'-bis(phenyl)amidinato)zir conium dichloride, PA1 Dimethylsilylene(n-butylcyclopentadienyl)(N,N'-bis(phenyl)amidinato)zirconi um dichloride, PA1 Dimethylsilylene(indenyl)(N,N'-bis(phenyl)amidinato)zirconium dichloride, PA1 Bis(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, PA1 Dimethylsilylenebis(N,N'-bis(phenyl)benzamidinato)zirconium dichloride PA1 Isopropylidenebis(N,N'-bis(phenyl)benzamidinato)zirconium dichloride, and the like. PA1 Biscyclopentadienylzirconium dichloride, PA1 Bis(methylcyclopentadienyl)zirconium dichloride, PA1 Bis(n-butylcyclopentadienyl)zirconium dichloride, PA1 Bis(n-butylcyclopentadienyl)zirconium dimethyl, PA1 Bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, PA1 Bis(pentamethylcyclopentadienyl)zirconium dichloride, PA1 Bis(pentamethylcyclopentadienyl)zirconium bis(bis(trimethylsilyl)methyl), PA1 Bis(pentamethylcyclopentadienyl)zirconium di(methoxymethyl), PA1 (Cyclopentadienyl)(methylcyclopentadienyl)zirconium dichloride, PA1 (Cyclopentadienyl)(n-butylcyclopentadienyl)zirconium dichloride, PA1 (Cyclopentadienyl)(indenyl)zirconium dichloride, PA1 (Cyclopentadienyl)(fluorenyl)zirconium dichloride, PA1 Cyclopentadienylzirconium trichloride, PA1 Cyclopentadienylzirconium trimethyl, PA1 Pentamethylcyclopentadienylzirconium trichloride, PA1 Pentamethylcyclopentadienylzirconium trimethyl, and the like. PA1 Dimethylsilylenebis(cyclopentadienyl)zirconium dichloride, PA1 Dimethylsilylenebis(methylcyclopentadienyl)zirconium dichloride, PA1 Dimethylsilylenebis(n-butylcyclopentadienyl)zirconium dichloride, PA1 Dimethylsilylenebis (n-butylcyclopentadienyl)zirconium bis(bis(trimethylsilyl)methyl), PA1 Isopropylidenebis(methylcyclopentadienyl)zirconium dichloride, PA1 Isopropylidenebis(n-butylcyclopentadienyl)zirconium dichloride, and the like. PA1 (1) a method in which at least one of the components (A) and (B) is mixed with the carrier (D), PA1 (2) a method in which the carrier (D) treated with the component (C) or a halogen-containing silicon compound is mixed with at least one of the component (A) and (B), PA1 (3) a method in which the carrier (D), the component (A) and/or component (B), and the component (C) or halogen-containing silicon compound are allowed to react, PA1 (4) a method in which after the component (A) or component (B) is carried on the carrier (D), the carrier (D) is mixed with the component (B) or component (A), PA1 (5) a method in which the contact reaction product of the components (A) and (B) is contacted with the carrier (D), or PA1 (6) a method in which upon contact reaction between the components (A) and (B), the carrier (D) is made to coexist.
However, these catalyst systems have low polymerization activities and are unsatisfactory for industrial production. Therefore, catalysts systems are desired which have high activities at reaction temperatures that are efficient in industrial processes and allowing production of high molecular weight polyolefins.
Also, it has been known that in order to increase moldability of ethylene base polymers, their melt tension needs be increased. For this purpose, study has been made on the improvement of the melt tension of ethylene base polymers with titanium base catalysts or chromium base catalysts of the Ziegler type. For example, a method of improving the moldability of ethylene base polymers obtained by a titanium catalyst of the Ziegler type by increasing their melt tension was disclosed (Japanese Patent Application Laid-open No. 90810/1981, Japanese Patent Application Laid-open No. 106806/1985).
Although the ethylene base copolymers obtained using titanium base catalysts or chromium base catalysts generally have improved melt tensions, they have a wide molecular weight distribution and contain large amounts of low molecular weight components (as evaluated by extraction with hexane) so that causes smoking when molding and molded articles tend to be sticky.
On the other hand, there has been known a method of producing polyethylene and ethylene-.alpha.-olefin copolymers using a metallocene catalyst composed of a metallocene compound and methylaluminoxane. The ethylene base polymers obtained by this method have a narrow molecular weight distribution and contain small amounts of low molecular weight components so that the problem of causing smoking when molding is solved but the problem of moldability remains because of their low melt tension.
In order to solve this problem, a study has been made on the use of two types of metallocene compounds in a metallocene catalyst system to improve the melt tension of a resulting polymer. For example, a method of producing polyethylene or ethylene-.alpha.-olefin copolymers has been disclosed which uses a combination of a metallocene complex having a non-crosslinking ligand and a metallocene complex having a crosslinking ligand with aluminoxane and optionally a carrier and an organic aluminum compound (Japanese Patent Application Laid-open No. 203904/1991, Japanese Patent Application Laid-open No. 213305/1992 (European Patent No. 452920)).
Further, Japanese Patent Application Laid-open No. 255436/1993, Japanese Patent Application Laid-open No. 255437/1993 (European Patent No. 515132), Japanese Patent Application Laid-open No. 155932/1993, and Japanese Patent Application Laid-open No. 155933/1993 (European Patent No. 516458) disclose methods of producing polyethylene or ethylene-.alpha.-olefin copolymers which use of a catalyst system composed of two types of metallocene complexes in combination with aluminoxane and optionally an organic aluminum compound or a catalyst system obtained by prepolymerizing this catalyst.
Further, Japanese Patent Application Laid-open No. 206922/1994, Japanese Patent Application Laid-open No. 206923/1994, and Japanese Patent Application Laid-open No. 206924/1994 (European Patent No. 598628) disclose methods of producing polyethylene or ethylene-a-olefin copolymers which use of a catalyst system composed of two types of transition metal compound complexes having at least two alkyl-substituted cyclopentadienyl ligands in combination with aluminoxane and optionally a carrier and an organic aluminum compound or a catalyst system obtained by prepolymerizing this catalyst.
The ethylene base copolymers obtained by these methods have narrow comonomer distributions and contain smaller amounts of low molecular weight components so that smoking when molding is reduced and stickiness of molded articles is also improved. However, the improvement of moldability is insufficient.
Accordingly, if a method of producing at high activities an ethylene base polymer is established which has a high melt tension strength and excellent moldability, contains smaller amounts of low molecular weight components, and is free of the problem of causing smoking when molding, then such method will have a high industrial value.
Therefore, it is an object of the present invention to provide a catalyst system which has a high activity at reaction temperatures efficient for industrial processes and enables one to produce high molecular weight polyolefins.
Another object of the present invention is to provide a catalyst and a method of producing polyolefins using the catalyst, which catalyst is capable of producing polyolefin that has a wide molecular weight distribution and an excellent moldability and contains smaller amounts of low molecular weight components.